This invention relates to valve assemblies. It has particular application to valves which are used typically in relatively inaccessible locations, e.g. valves of the type which are used in subsea pipelines.
The components of valves, e.g. gate valves which are used in subsea locations, are subject to wear, corrosion and erosion and hence periodically need replacement. It has been proposed to mount the flow control components of such valves, typically the gates and seats, in an insert which can be removably mounted in a receiver receptacle. The receptacle can be coupled to the flow line which the valve controls. This enables the insert to be removed either by a diver or by a remotely operated vehicle for the replacement of the valve components. In such arrangements it is necessary to provide an adequate seal between the insert and the receiver. Known arrangements use inserts or receivers which are relatively complex to produce.
A type of insert valve is shown in the U.S. patent application Ser. No. 07/555,055, of David Garnham, filed July 19, 1990 and assigned to the same assignee as the present application. This application discloses a removable body portion carrying the flow controlling elements, a receptacle which receives the body and axially movable sealing members. The sealing members have metal seals positioned thereon for engagement with the body when it is inserted into the receptacle. Bifurcated levers are mounted on the sealing members and are contacted by the body upon insertion to urge the metal seals into contact with the face of the removable body portion.
The K. B. Bredtschneider et al. U.S. Pat. No. 3,179,121 discloses a ball valve construction with a ball and seats manually removable as a unit. The seats seal against the valve body with elastomeric seal means on a tapered surface.
The M. R. Jones U.S. Pat. No. 3,589,674 discloses another ball valve structure with a second pressure balancing stem in which the ball, seats and balance stems are manually removable as a unit.
The J. A. Burkhardt et al. U.S. Pat. No. 3,799,191 discloses a gate valve structure with a removable body containing the gate, seats, stem and stem operating means. The removable body is secured to the valve body by a lock ring.
The R. L. Ripert U.S. Pat. No. 4,387,735 discloses a valve structure removable from a pipeline wherein the valve is received within a support structure attached to the pipeline. The support structure has seal rings mounted therein which a worm gear mechanism activates into engagement with the removable valve structure to form a fluid tight conduit.
The R. L. Ripert U.S. Pat. No. 4,431,022 discloses a removable valve structure received within a support structure similar to that of the '735 patent. The valve structure has all components mounted therein, including a sealing means on each end of the valve which is biased outwardly to engage parallel plates on the support structure. A pressure responsive means for moving the seal rings inwardly during installation and removal is also disclosed.
The J. E. Lawson U.S. Pat. No. 4,874,008 discloses a valve mounting structure whereby hydraulic studs are used to secure a valve body between mounting members which are part of a block manifold used in oil and gas production.